Hex #669799 or rgb(102,151,153) in RGB space is the tint of cyan. It has hue angle of 182.35 degrees, value = 60 and saturation = 33. #669799 can be obtained by mixing 4 colors: 3 drops of magenta, 3 drops of cyan, 3 drops of green, 1 drop of white.
Nearest safe hex - #669999. Below you can see the block with #669799 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #669799 to the mixer and play with it.